Transceivers are used in optical communications networks to retransmit optical signals or to convert signals between optical and electrical domains. Recently, digital data processors have been added to transceivers, enabling new functions beyond mere signal retransmission and conversion. Nowadays, transceivers may perform packet processing, filtering, as well as participate in network testing as inline probes.
New functionalities of transceivers bring in additional requirements, such as an ability of a “graceful” shutdown in case of a power loss. This graceful shutdown may include a message that an electrical power loss is imminent, which is termed in the field as a “dying gasp” functionality.
A transceiver is typically hosted by network communications device, such as a router, a switch, a gateway, a circuit pack, customer premises equipment (CPE) box, or some other type of networking equipment. Presently, a transceiver relies on its hosts to detect and report power interruptions. The transceiver remains powered by the host via a buffer capacitor having enough charge stored to enable a message to be sent out. The power loss detection circuitry, the message generation circuitry, as well as the buffer capacitor are all provided by the host.
It may be advantageous to provide a shutdown warning capability in a transceiver device itself Unfortunately, transceivers rarely have enough room on their printed circuit boards (PCBs) to accommodate large and bulky elements, such as buffer capacitors for storing enough electrical charge for a graceful shutdown and/or for sending out a “dying gasp” message.